*2.10. Packaging Test-Application of CS/PVOH/HNT and CS/PVOH/TO@HNT Films as Coating on Fresh Kiwifruits*

In Figure 11 of uncoated kiwifruits and coated kiwifruits with CS/PVOH, CS/PVOH/10HNT, and CS/PVOH/10TO@HNT solution after 21 days of storage at 25 ◦C and ambient humidity are shown. As it is obtained from the uncoated kiwifruits the weight loss change is visible from the 3rd day of storage. The visible changes for uncoated samples are more visible on the 6th day and the deterioration increased until the 15th day when the uncoated kiwi fruits were rejected. In the kiwifruits coated with pure CS/PVOH solution the deterioration is visible 3 days later in the 6th day and is increased until the 15th day when also these samples were rejected. For the kiwifruits coated with CS/PVOH/10HNT and CS/PVOH/10TO@HNT solution, the deterioration is much slower. The first visible weight loss change is starting for the kiwifruits coated with CS/PVOH/10HNT solution on the 12th day while for the kiwifruits coated with CS/PVOH/10TO@HNT solution three days later on the 15th day. From the 15th to 21st day of storage as it is obtained (see the last image in the down part of Figure 11) the deterioration of kiwifruits coated with CS/PVOH/10HNT was much more accelerated than the kiwifruits coated with CS/PVOH/10TO@HNT solution which are in a much better optical condition in the last day of the experiment. To conclude a significant deceleration of kiwifruits deterioration was obtained for all coated samples. The uncoated kiwifruits deterioration starts on the 3rd day, while for the kiwifruits coated with CS/PVOH, CS/PVOH/HNT, and CS/PVOH/10TO@HNT solution on the 9th, 12th, and 15th day correspondingly. At this point, it must be mentioned, that the delayed deterioration of the kiwi fruits could be attributed also to the antimicrobial activity of the tested films. Although the films were studied for certain food-borne bacteria, it is likely to have also antimicrobial activity against other spoilage microorganisms, leading to extended life.

CS/PVOH/10TO@HNT solution three days later on the 15th day. From the 15th to 21st day of storage as it is obtained (see the last image in the down part of Figure 11) the deterioration of kiwifruits coated with CS/PVOH/10HNT was much more accelerated than the kiwifruits coated with CS/PVOH/10TO@HNT solution which are in a much better optical condition in the last day of the experiment. To conclude a significant deceleration of kiwifruits deterioration was obtained for all coated samples. The uncoated kiwifruits deterioration starts on the 3rd day, while for the kiwifruits coated with CS/PVOH, CS/PVOH/HNT, and CS/PVOH/10TO@HNT solution on the 9th, 12th, and 15th day correspondingly. At this point, it must be mentioned, that the delayed deterioration of the kiwi fruits could be attributed also to the antimicrobial activity of the tested films. Although the films were studied for certain food-borne bacteria, it is likely to have also antimicrobial activity against other spoilage microorganisms, leading to extended life.

**Figure 11.** Images of uncoated kiwifruits, coated with CS/PVOH solution kiwifruits, coated with CS/PVOH/10HNT solution kiwifruits and coated with CS/PVOH/10TO@HNT solution kiwifruits stored at 25 °C and ambient humidity at zero, 3rd, 6th, 9th, 12th, 15th and 21st day. **Figure 11.** Images of uncoated kiwifruits, coated with CS/PVOH solution kiwifruits, coated with CS/PVOH/10HNT solution kiwifruits and coated with CS/PVOH/10TO@HNT solution kiwifruits stored at 25 ◦C and ambient humidity at zero, 3rd, 6th, 9th, 12th, 15th and 21st day.

#### **3. Conclusions 3. Conclusions**

Concluding this study, according to the TG and FTIR results the proposed modified adsorption process led to ~35 wt.%. of TO loading onto HNT nano-clay combined with very good incorporation. Furthermore, the FTIR results indicate a prevailing Concluding this study, according to the TG and FTIR results the proposed modified adsorption process led to ~35 wt.%. of TO loading onto HNT nano-clay combined with very good incorporation. Furthermore, the FTIR results indicate a prevailing physisorption mechanism as it is compared to chemisorption. This led to a controlled release mechanism of the TO which was confirmed by the antibacterial tests. We are heading in the same direction if we interpret the XRD results shown, that the thymol was adsorbed on the external surface of the HNT in a high order and thus, such molecules could be easily released. The comparison of the HNT with the TO@HNT nanostructures behaviour via SEM, EDS, and XRD measurements implies that the dispersion of the second one in the CS matrix is higher than the relevance of the first one, which is beneficial for the final developed film. Even though CS/PVOH/15TO@HNT exhibits higher antioxidant and antibacterial activity, the CS/PVOH/10TO@HNT exhibits a higher water-oxygen barrier. According to the XRD measurements, this result originates from dispersion collapse for higher nanohybrid addition. Such results were verified by the in-vivo experiments of kiwi fruits preservation where the uncoated food started to decline on the 3rd day, the coated

food with CS/PVOH/15HNT film started to decline on the 12th day, and the coated food with CS/PVOH/15TO@HNT film started to decline at the 15th day. The rejection day of the uncoated kiwi fruits was the 15th day while the rejection of the coated fruits was the 21st day. The final situation of the CS/PVOH/15TO@HNT kiwi samples was better than the relevant of the CS/PVOH/15HNT coated samples. Finally, UV-vis and SEM measurements show that the TO addition is beneficial for the film's transparency and to the HNT dispersion in the CS matrix.

As a final result of this study, we could say that a promising active packaging film was developed through a more environmentally friendly procedure and tested successfully for kiwi fruit preservation. As future work, we could say that this product should be also tested with other food kinds and develop an industrial process for bulk film production via a scale-up procedure.
